High Voltage Hijinks
- Thread starter Hal Harvey
- Start date
drgonzo1969
Well-known member
I’m approaching the finish line on my first amp build (Thunderdome) so naturally I gotta get rolling #2. I bought some pcbs from @Asdrael (Thanks again!) a while back for the Deliverance amp. He also had a handy mouser BOM that made sourcing a piece of cake. Populating the PCBs with all the sexy red capacitors was very pleasant. I have a cart ready on the amplified parts website for the chassis, OT and other off board parts. Waiting for sale to pull trigger. Still need to source custom power transformer. I have never sourced a custom power transformer before. Any suggestions on where to start looking for a quote? These are the specs @Asdrael listed.
prim.: your wall
sec. : 340V/0,3A (main HT)
14V/1,0A (relays + preamp heaters)
50V/0,06A (bias)
6,3V/3,50A (power tube heaters)
prim.: your wall
sec. : 340V/0,3A (main HT)
14V/1,0A (relays + preamp heaters)
50V/0,06A (bias)
6,3V/3,50A (power tube heaters)
Asdrael
Well-known member
Been a while since I opened up mine and forgot that I made it intentionally sexy
I hope you had a good and easy time populating. If you saw anything weird let me know in case I do a v2.For the transformer, not sure in the US. I know some people get an off the shelf one and add a secondary one for the 14V. I went with a toroidal, which is more compact and often times cheaper. Looking back at it I would probably overspec the 14V and bump it to 1.5A in case your manufacturer ends up being cheap on the wire…
Edit: I zoomed in and noticed you don't have anything on the FX loop yet. Don't forget to jump it if you don't plan on adding an external FX loop solution otherwise you won't get sound.
JohnnyCreepy
Well-known member
Been working and fixing some mistakes in my ex-Simmswatts-now-superbass/model t. Doing some bass cutting as second time on rehearsals got me thinking there’s just too much bass and doing high gain with pedals leads bassy mush and preamp hits headroom limit.
- V1 shared cathode bypass reduced from 220uF to 3.3uF
- Rewiring all potentiontiometes other way around because I cannot learn from my mistakes and soldered 1&3 lugs wrong way on all other than presence pot
- Tonestack bass pot value increase from 250k to 1M
- Tonestack 470p silver mica to HV poly cap
- Power section grid leak value reduce still to do. Now they’re 180k so maybe I’ll try 120k?
- NFB switch has two values and off option and there’s 100p and 200p caps parallel different nfb resistors. Now when NFB is on the sustain has some oscillating modulation going on so maybe I’ll just add pot before first NFB resistor for tweaking the amount right for my needs. If I’d play drone current state would be sweet…
JohnnyCreepy
Well-known member
I honestly don’t know what I did finally caused 50/100hz hum disappear which I’ve been struggling when circuit was all stock with og pcb. But now I’m there where I want with hum free amp and acceptable hiss remaining. Was it PA grid leak resistor value reduce? Were silver micas causing it? Or something else?
Tonestack works now effectivily, diming channel volumes brings nice grit and cleaner sound is possible with ch volume down & master up. Tomorrow brings the true test with 2x15 cab.
Tonestack works now effectivily, diming channel volumes brings nice grit and cleaner sound is possible with ch volume down & master up. Tomorrow brings the true test with 2x15 cab.
Asdrael
Well-known member
I have asked around, and in the US for transformers people mostly use Heyboer and Mercury Magnetic but Sour Sound and Musical Power Supplies were also mentioned.
vigilante398
Authorized Vendor
I use Musical Power Supplies a lot in the US, they make quality stuff at reasonable prices. Also I haven't put them in an amp build, but Edcor is another great supplier for US made iron, I've seen a couple builds from other people with Edcor transformers.
And for @drgonzo1969 I wouldn't recommend trying to get a custom transformer if it can be avoided, first try to find something off the shelf that's at or close to the specs you need.
Asdrael
Well-known member
Blame me - I made the pcb require a 14V supply for DC heaters. Hard to find stock. My next versions will have a 12V Recom exactly for this reason…
vigilante398
Authorized Vendor
That's why the last amp design I did (I don't do many) used 5V relays so I could use a rectified 6.3V line and regulate it down, makes PT selection a lot easier
drgonzo1969
Well-known member
Amplified parts just started memorial sale. Gonna dig through their transformers and see if something they have will work.
Asdrael
Well-known member
Sooooo... who goes first?
Passinwind
Well-known member
Since I just got my new one going properly yesterday, looks like it'll be moi. New output transformer shipped from Heyboer two days ago, so I'll be doing proper guts shots soon.Sooooo... who goes first?